2 * CDE - Common Desktop Environment
4 * Copyright (c) 1993-2012, The Open Group. All rights reserved.
6 * These libraries and programs are free software; you can
7 * redistribute them and/or modify them under the terms of the GNU
8 * Lesser General Public License as published by the Free Software
9 * Foundation; either version 2 of the License, or (at your option)
12 * These libraries and programs are distributed in the hope that
13 * they will be useful, but WITHOUT ANY WARRANTY; without even the
14 * implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
15 * PURPOSE. See the GNU Lesser General Public License for more
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with these libraries and programs; if not, write
20 * to the Free Software Foundation, Inc., 51 Franklin Street, Fifth
21 * Floor, Boston, MA 02110-1301 USA
23 /*%% (c) Copyright 1993, 1994 Hewlett-Packard Company */
24 /*%% (c) Copyright 1993, 1994 International Business Machines Corp. */
25 /*%% (c) Copyright 1993, 1994 Sun Microsystems, Inc. */
26 /*%% (c) Copyright 1993, 1994 Novell, Inc. */
27 /*%% $TOG: isdlink.c /main/4 1999/09/29 15:03:15 mgreess $ */
29 static char sccsid[] = "@(#)isdlink.c 1.4 89/09/01 Copyr 1988 Sun Micro";
33 * Copyright (c) 1988 by Sun Microsystems, Inc.
40 * Double link list functions
43 #include "isam_impl.h"
45 /* _isdln_base_insert () - Insert element into list (at the front) -----------*/
46 void _isdln_base_insert (register char *base, register struct dlink *l,
47 register struct dlink *e)
49 e->dln_forward = l->dln_forward;
50 l->dln_forward = (char *)e - base;
52 e->dln_backward = (char *)l - base;
53 ((struct dlink *)(base + e->dln_forward))->dln_backward = (char *)e - base;
56 /* _isdln_base_append () - Append element to list (at the end) -------------*/
57 void _isdln_base_append (register char *base, register struct dlink *l,
58 register struct dlink *e)
60 e->dln_backward = l->dln_backward;
61 l->dln_backward = (char *)e - base;
63 e->dln_forward = (char *)l - base;
64 ((struct dlink *)(base + e->dln_backward))->dln_forward = (char *)e - base;
67 /* _isdln_base_remove () - Remove element from list -------------------------*/
68 void _isdln_base_remove (register char *base, register struct dlink *e)
70 ((struct dlink *)(base + e->dln_backward))->dln_forward = e->dln_forward;
71 ((struct dlink *)(base + e->dln_forward))->dln_backward = e->dln_backward;
74 /* _isdln_base_first () - Return first element of the list -------------------*/
75 struct dlink * _isdln_base_first(register char *base, register struct dlink *l)
77 struct dlink *val = (struct dlink *)(base + l->dln_forward);
80 if (NULL == (struct dlink *)(base + l->dln_forward) &&
81 NULL == (struct dlink *)(base + l->dln_backward))
82 _isdln_base_makeempty(base, l);
88 /* _isdln_base_next () - Return next element in the list --------------------*/
89 struct dlink * _isdln_base_next(register char *base, register struct dlink *l)
91 return (((struct dlink *)(base + l->dln_forward)));
94 /* _isdln_base_prev () - Return previous element in the list ----------------*/
95 struct dlink * _isdln_base_prev(register char *base, register struct dlink *l)
97 return (((struct dlink *)(base + l->dln_backward)));
100 /* _isdln_base_makeempty () - Make head of empty list -----------------------*/
101 void _isdln_base_makeempty(register char *base, register struct dlink *l)
103 l->dln_forward = l->dln_backward = (char *)l - base;
106 /* _isdln_base_isempty () - Test if list is empty---------------------------*/
107 int _isdln_base_isempty(register char *base, register struct dlink *l)
109 return (l->dln_forward == (char *)l - base &&
110 l->dln_backward == (char *)l - base);